The invention relates generally to hermetically sealed electronic packages. More particularly, the invention relates to electronic packages employing organic devices and having a low temperature hermetic seal and methods of making the same.
Organic devices are low cost and high performance alternatives of the silicon semiconductor devices and are employed in various applications, such as, organic light emitting diodes (OLEDs), organic light sensors, organic transistors, organic solar cells, and organic lasers.
However, these organic devices may require protection from environmental elements such as, moisture or oxygen, to prevent degradation of the device. Most of these devices are made of a layered structure incorporating different layers of materials each having diverse functionalities. One common way to protect these devices includes providing encapsulation to the layered structure. Typically, the procedure to encapsulate the organic device includes sandwiching the organic device between a substrate and an encapsulation layer such that there is a continuous perimeter seal around the device. Often, sheets of glass, metal, or plastics having barrier coatings are used to sandwich the device. These sheets are joined together with adhesives, often based on epoxies. While the sheet materials provide excellent hermetic properties, the adhesives may not.
In the past, thinner layers of adhesives have been employed between the substrate and the encapsulation layer to limit the diffusion of undesirable elements such as, water and/or oxygen into the package. While the rate of diffusion is reduced by employing thinner layers of adhesives, the adhesive remains quite permeable to environmental elements. As will be appreciated, adhesives having fewer interfacial voids at the unions of the adhesive and the sheet materials lead to slower diffusion rates of the adhesive into the package during fabrication, thereby resulting in insufficient coverage of the encapsulant perimeter around the device. Additionally, moisture absorber or getters may be employed on the surface of the encapsulant or may be incorporated into the package to prevent any intruding water from entering the package. However, these materials are expensive and also have limited capacity in terms of preventing the permeation of environmental elements into the encapsulant.
Accordingly, there is a need for electronic packages employing sealing materials that reduce the permeation of environmental elements through the edges of the devices, as compared to conventional devices.